NO. 2286. THE NEW COPEPOD FAMILY SPHYRIIDAE— WILSON. 555 



ihat thus searches by burrowing for some convenient source of its 

 food supply. But we can not argue either that such genera belong 

 to the Lernaeidae simply because they show torsion, or that the 

 amount and direction of torsion is constant enough to furnish spe- 

 cific characters. Since the male never burrows but remains free 

 upon the outside of the body of the host, or upon the body of the 

 female, it never exhibits torsion. 



Food. — As in the Lernaeidae, the simple fact that the females 

 thus burrow through the tissues of the host until their mouth is 

 brought in contact with some blood vessel is sufficient proof that the 

 fish's blood constitutes their food. The male is provided with a 

 well developed sucking proboscis and with the ordinary piercing 

 mouth parts found in other male parasitic copepods. The body also 

 contains digestive and excretory glands as well developed as those of 

 tlio Lernaeopod males, and in addition the posterior portion of the 

 digestive tract is fully developed, with an anus opening to the exte- 

 rior. It seems reasonable, therefore, to assume that the male also 

 feeds upon the blood of the host, at least until it takes a position 

 on the body of the female. And even then, so deeply is the female 

 buried in the tissues of its host, the male would not have far to crawl 

 in order to reach the fish's skin. 



Hosts. — The species of this family are confined entirely to salt 

 water fishes, and further to deep-sea forms, or at least to those that 

 live in the open ocean. The two species of the new genus Paeon and 

 the single species of Tri/paphyluin are found in the gill cavity of 

 sharks. The other species are found either in the gill cavity or on 

 the outside surface of various deep-sea fishes ranging from the Afri- 

 can cod to the common rat-tail off our North American coast. 



Parasites. — All the specimens examined by the author except those 

 of Paeon versicolor have proved to be remarkably clean and free 

 from parasities or messmates, either animal or vegetable. In a single 

 specimen of Rehelula houmeri., taken from Macrovrus hairdii, the 

 part of the body which hung free outside the fish's skin was com- 

 pletely covered with a dense growth of algae. 



EXTERNAL MORPHOLOGY. 



The body of a Sphyriid is divided into three distinct regions — a 

 cephalothorax made up of the head and first thorax segment, a long 

 slender neck, chitinous and sometimes filose, and a trunk made up of 

 a little of the posterior end of the fourth thorax segment, all of the 

 fifth and sixth segments and the abdomen. 



In Opimia the cephalothorax is smooth and destitute of processes 

 or horns, in all the other genera it is profoundly modified by out- 

 growths and enlargements. These may take the form of soft pro- 

 cesses or chitin horns. The soft processes are found on the front 



